The present invention pertains to drop-in anchors. More particularly, the present invention pertains to a deep set drop-in anchor that properly self-sets even in deeply drilled bores, and is readily removable so that no portion of the anchor extends exteriorly from the structure after use.
Various types of anchors are in wide-spread use in the construction industry. Typically these anchors are used to provide a means to anchor or secure an object to a structure, such as a wall or floor. In many applications, the object is secured to a solid (e.g., concrete) structure. These anchors are inserted into an opening (e.g., a bore or hole) in the structure and engage the walls of the opening. The anchors can be either removable or non-removable, e.g., permanent.
Removable anchors are used, in one application, for temporary supports in tilt-wall construction. In such a use, the anchor is used to secure a shoe to a concrete floor that is temporarily brace a wall as wall is being lifted or tilted into position. In this application, once the wall is set and secured in place, the shoe must be removed, as does any part of the anchor that is above the surface of the floor.
Anchors are known that include a split sleeve having inwardly tapered lower wall an upper threaded portion. A plug is forced into engagement with the tapered lower walls to frictionally engage the sleeve with the walls of the opening. A bolt or threaded rod is, then engaged with the sleeve threads to secure the bolt or rod with the anchor.
Another known type of removable anchor is a pin drive anchor. This type of anchor uses a sleeve that is inserted into a hole or bore formed in the structure. A sectioned or split plug having a reduced diameter is inserted into the sleeve and is set into place by forcing a setting pin or tool against the plug element. The force on the pin urges the sleeve outwardly to engage the inner walls of the bore. The sleeve can include threads for receiving a bolt or like threaded fastener.
Still another type of removable anchor is a coil anchor. The type of anchor includes a threaded shank and a coil that is wound around a portion of the thread. The shank and coil are inserted into a bore having a predetermined depth. The shank is rotated so that the coil engages the walls of the bore while it is engaged by the shank threads.
One type of non-removable anchor, referred to as a wedge anchor, includes a split sleeve with a reversed tapered wedge element formed at the end of a threaded shank. The sleeve and shank element are inserted into the bore and the shank is pulled so that the reversed tapered sides of the wedge engage the sleeve and urge the sleeve portions outwardly to engage the inner walls of the bore.
Each of these types of anchors has its drawbacks. First, the wedge anchor cannot be removed after it is installed. Although this type of anchor has a high pull-out strength, it cannot be used in applications where the anchor is used in a temporary installation and is removed after use.
The pin drive anchor, although in wide-spread use, must be used with a tool or pin of a predetermined length. In addition, these anchors typically have a limited depth to which they can be installed. This results in reduced loading capabilities.
Like the pin drive anchor, the coil anchor also has limitations vis-a-vis anchor depth and coil engagement with the bore walls. If the bore depth is too great, and the anchor is not properly set, the shank may not fully engage the coil, thus resulting in less than intended load levels. In addition, these anchors typically require that a high torque be applied to the bolt to properly set the anchor.
Accordingly, there exists a need for a drop-in anchor that can be removed after use. Desirably, such an anchor includes a wedge or plug that can be properly set within a sleeve regardless of the depth at which the anchor is set. Most desirably, such an anchor uses bolt for both setting the plug (e.g., as a setting tool) and securing an object to the structure in which the anchor is set. Also most desirably, the anchor can be used with a standard a reusable bolt.
A drop-in anchor includes a partially threaded sleeve, a plug, a threaded shank having a through-bore and a setting member or tool. The present drop-in anchor provides a fastening system in which the fastening member (e.g., the bolt) can be removed after use so that no part of the fastening member does not extends from the structure after removal, in which the anchor is installed.
The anchor sleeve has a threaded region and a split region having at least two longitudinal channels formed therein. The channels define sections. In a current embodiment, the split region has four longitudinal channels defining four substantially identical sections. The split region has inwardly tapered inner walls.
The plug is configured for engagement with the sleeve at the split region. The plug has a top surface and defining a tapered shape. Preferably, the taper of the plug complements the tapered inner walls of the sleeve split region.
A shank, preferably formed as a shoulder bolt, has a threaded portion and a through-bore extending longitudinally therethrough. The threaded portion is configured for threaded engagement with the sleeve threaded region. In the preferred embodiment in which a shoulder bolt is used, the bolt shoulder is configured to engage an upper lip of the sleeve to assure proper positioning of the bolt in the sleeve.
The setting member is configured for insertion into the bolt through-bore. The setting member engages the plug top surface. A force exerted on the setting member drives the plug into the sleeve split region so as to drive the split region sections axially outwardly.
The setting member can be formed as a pin having a head. Striking the setting member head drives the setting member head into contact with the bolt head and drives the plug into the split region sections which drives the sections axially outward. This secures the anchor in the structure.
A method for securing an anchor in an opening in a structure is also disclosed.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.